1. Field of the Invention
The present invention relates to a metallic tack for use upon attaching a button for jeans to its cloth and more particularly to a button attaching tack which never induces puckering phenomenon in the cloth when the cloth is pierced therewith.
2. Description of the Related Art
According to a conventional tack 1xe2x80x2 for button disclosed in Japanese Utility Model Publication No. 63-10729, as shown in FIG. 13, a cylindrical post 4xe2x80x2 stands on the center of a seat plate 3xe2x80x2. The post 4xe2x80x2 is made of metal and an end of the post 4xe2x80x2 is ground to have a head 5xe2x80x2 shaped in quadrangular pyramid. Concave portions 21xe2x80x2 are formed in the post 4xe2x80x2 below the head 5xe2x80x2 so as to facilitate deformation of the head 5xe2x80x2. After this tack 1xe2x80x2 is pierced into cloth, it is inserted into a boss portion of a metallic button. At this time, the head 5xe2x80x2 is pressed, so that it is deformed through the concave portions 21xe2x80x2 in the post 4xe2x80x2 thereby the head being fixed in the boss portion.
Further, according to a tack 1xe2x80x2 for button disclosed in Japanese Utility Model Laid-Open Publication No. 60-69008, as shown in FIG. 14, a cylindrical post 4xe2x80x3 stands on the center of a seat plate 3xe2x80x3. An end of the post 4W is formed to have a conical head 5xe2x80x3 protruded with respect from an outer periphery of the post 4xe2x80x3. Then, plural stages of truncated cone-shaped engaging portions 8xe2x80x3 protruded with respect to the outer periphery of the post 4xe2x80x3 like the head 5R are formed in the post 4xe2x80x3 below the head 5xe2x80x3. After this tack 1xe2x80x3 is pierced into cloth, it is inserted into an attaching hole formed in a boss portion of resin made button. Consequently, the tack for button is fixed in the boss portion by means of the head 5xe2x80x3 and the engaging portions 8xe2x80x3.
The aforementioned tack 1xe2x80x2 for button shown in FIG. 13 is different from a tack of the present invention in engagement manner between the tack 1xe2x80x2 and the boss portion of a button. In case of this conventional tack 1xe2x80x2, it is fixed to the boss portion of a metallic button by deforming a front end of the tack 1xe2x80x2 by pressure. Therefore, the tack 1xe2x80x2 is so constructed that the post 4xe2x80x2 and head 5xe2x80x2 are connected to form a smooth surface and has no engaging portion which protrudes with respect from the post. Thus, there is such a problem that this tack cannot be fixed easily to the boss portion of a resin button.
Further, the tack 1xe2x80x3 for button shown in FIG. 14 has a problem that because the head 5xe2x80x3 formed at an end of the post 4xe2x80x3 is conical, when the tack is pierced into cloth, the head 5xe2x80x3 makes facial contact with the cloth so that a large resistance is generated thereby often leading to the puckering phenomenon.
The present invention has been accomplished in view of the above described problems and an object of a main aspect of the invention is to provide a tack for button for use upon fixing a jeans button to jeans cloth, wherein a head thereof is formed in a shape not making a facial contact with cloth producing a large contact resistance but making a linear contact with cloth producing a less resistance when the tack for button is pierced into the cloth, so that no puckering phenomenon occurs. This tack has a simple structure and tough engaging mechanism so that it can be engaged with the boss portion firmly and fixed thereto.
It is also an object of the present invention is to provide a tack for button, wherein a proximal periphery of the head is protruded outwardly of a post so that the head of the tack engages firmly with the boss portion of a button, or a tack for button capable of being pierced easily, which can be engaged with the boss portion of a button with corners of the head.
Another object of the present invention is to provide a tack for button, wherein the corners of the head are exposed more so that they can be engaged firmly when the proximal end of the head is engaged with the boss portion of the button, thereby the engaging performance is improved.
A further object of the present invention is to provide a tack for button, wherein the post thereof can be engaged firmly with the boss portion of the button by means of engaging protruding portion disposed above the post, thereby the engaging performance is improved.
Another object of the present invention is to provide a tack for button, wherein the shape of the head thereof is formed in a pointed shape allowing it to be pierced into cloth easily, thereby facilitating the piercing operation.
Another object of the present invention is to provide a tack for button and a boss portion, which are formed using specified materials in a shape matching with each material, thereby achieving easy and firm engagement between the tack for button and the boss portion.
To achieve the above object, according to the main aspect of the invention, there is provided a tack for button, wherein a post stands upward from the center of a flat seat plate; a polygonal pyramid shaped head is formed integrally at an end of the post; and sharp and strong corners provided on a proximal periphery at a lower end of the head are protruded out of a peripheral face of the post so as to form an engaging portion, thereby the engaging performance of the head being intensified.
Preferably, the proximal periphery at a lower end of the polygonal pyramid shaped head, which is provided at an end of the post, is protruded out of an outer peripheral face of the post, thereby the engaging performance of the head being intensified.
Alternatively, part of the proximal periphery of the corner in the polygonal pyramid head, which is provided at an end of the post, is located inside with respect to the outer peripheral face of the post, thereby the engaging performance and piercing function of the head being intensified.
Preferably, a bottom face of each of the corners of the head extends inwardly at a border between the head and the post so that a neck portion thinner than the post is formed, thereby the engaging performance of the head being intensified.
Also preferably, a neck portion thinner than the post is formed under the head formed on the tack; an engaging protruding portion is provided on the post below the neck portion so as to protrude therefrom, thereby the engaging performance of the tack being intensified.
Preferably, a vertical angle of each of peripheral faces formed on the polygonal pyramid head, which is provided at an end of the post, is in a range of 20 to 40xc2x0 to make the head sharp, thereby the piercing performance of the head being intensified.
Preferably, the tack is formed of metal and the boss portion in which the tack is to be inserted is formed of thermoplastic resin, thereby the engaging performance between the tack and the boss portion of a button being intensified.